1. Field of the Invention
The present invention pertains to an opto-electronic head in which an optic fiber is coupled to a light emitting or receiving semi-conductor device or to another optic fiber. The invention pertains more es pecially to the means and elements, incorporated into the opto-electronic head, used to align and keep the optic fiber and the semi-conductor device together with high precision. The invention also pertains to a method of alignment along one and the same optical axis.
2. Description of the Prior Art
The coupling of an optic fiber with a light emitting or receiving semi-conductor device is well known: the said coupling is the necessary point of passage in any system using optic fibers. Every optic link requires a transmitter at one of its ends and a receiver at the other, to transform the data signals to be processed from electronic signals into optic signals and vice versa. It is also well-known that, owing to the minute size of the active surfaces of emitting or receiving semi-conductors and of the cores of the optic fibers, the coupling of these components requires precise alignment.
Regardless of the structure of existing opto-electronic heads, this alignment is increasingly being done dynamically (i.e. with the emitter and the receiver in operation, with the receiver analyzing the light transmitted by the optic fiber). The two components are fastened by different means: either with a drop of bonder, polymerized by ultra-violet or thermal radiation, or by metal remelting. Bonding is irreversible whereas solder can be remelted if the alignment has to be re-adjusted. But, in both cases, an external form of energy (heat or light) has to be supplied.
The disadvantage of supplying external energy is that the energy is not sufficiently localized. Thus, certain elements of the opto-electronic head, such as the laser chip, its support and the bonder or solder which fixes the optic fiber, also get heated. Now the materials of which these parts are made have different natures. They have different coefficients of expansion and the optical alignment, when the opto-electronic head is cooled, is no longer the alignment when the head is heated during the adjusting operation. Furthermore, the laser diodes or light-emitting diodes release heat and are cooled during operation by means of a Peltier element, the effect of which is countered by the addition of external energy.